Production of acetone



Patented Dec. 20, 1932 UNITED STATES PATENT OFFICE BANS MEEBWEIN AND HEINRICH MORSCHIEL, OI KONIGSBERG, GERMANY, ASSIGNOBS TO THE FIRM SCHERING-KAHLBAUM A. G., BERLIN, GERMANY raonuc'rron or acn'rona No Drawing. Application filed June 5, 1928, Serial No, 288,121, and in Germany April 22, 192?.

.Our invention refers to the production of acetone and more especially to means whereby acetone can be produced from certain organic compounds including acetaldehyde and ethyl alcohol in a particularly economical and efiicient manner.

lVe have found that if acetaldehyde vapour is caused to pass together with steam in excess over suitable contact substances heated to 300 to 500 C., carbon dioxide and hydrogen will be split off, and the acetaldehyde will thus be readily converted into acetone.

As suitable contact substances may be used mixtures of an oxide of tin with an oxide of thorium, zirconium, zinc or cerium or an oxide of another rare earth metal. Mixtures of the oxides of tin and cerium have been found to be particularly efiicient. The oxides may also be replaced by salts of the metals above mentioned, which under the particular conditions of operation will be converted into the oxides, for instance carbonates, formates, acetates and oxalates.

The proportions of the single oxides in these mixtures may be varied within wide limits. Instead of using such oxide mixtures, we may also use mixtures of the oxides of tin with the carbonates of an earth alkali. All

these contact masses have anexcellent catalytic efiiciency and great stability. Instead of the carbonates also such salts of earth alkalis can be used which are converted during the operation into the carbonates, such as for instance acetate or oxalates. The proportions of the several constituents of these mixtures can also be varied within wide limits.

The carbonates of the earth alkalis, if used by themselves, will not bring about a conversion of the mixture of acetaldehyde and steam into acetone, but will exert in a well known manner a condensing action on the acetaldehyde, leading to the formation of crotonic aldehyde and other products boiling at higher temperature and not readily soluble in water. Contrary to what could be expected, if the earth alkali carbonates are combined with the oxides of tin, this condensing act-ion will not show,but a smooth and practically complete conversion of acetaldehyde into acetone will take place without 'sponded to the calcu any material formation of by-products.

It is well known that ethyl alcohol can be converted under the influence of catalysts having a dehydrating effect into acetaldehyde at an elevated temperature. Such catalysts are the oxides of tin. Therefore the catalysts mentioned above as inducing the conversion of acetaldehyde into acetone, and containing oxides of tin, are also adapted for converting ethyl alcohol in a single operation direct into acetone. For the conversion of ethyl alcohol as well as acetaldehyde into acetone a mixture of stannic oxide or stannous oxide with cerium oxide has shown to be an excellent catalyst. If this catalyst is used, 93 to 95 per cent of the calculated amount of acetone can be obtained from ethyl alcohol as well as from acetaldehyde. If the exhaust gases are washed with high boiling solvents or by adsorption with active carbon the yield can be improved further by several per cent. The reaction product after a single passage over the catalyst at 420 C. does not contain any alcohol nor any acct-aldehyde, only a very smallfquantity about .6percent) of acetic acid.

As is well known, all catalytic processes depend both technically and commercially upon the stability or duration of life of the catalysts used. We have found that during an operation lasting three weeks without any interruption, in which a catalyst composed of tin oxide and cerium oxide was used, the yield of acetone only changed from 94 per cent recovered at the beginning to 92 er cent recovered at the end of the three wee s. The gas composition at the end of the operation was as follows:

The quantity of gases split off correated quantity.

The catalyst mixtures requlred in this process are obtained either by direct mixing of the single catalysts or by slmultaneous preci itation of the metal salts, quite especially t e nitrates, chlorides or acetates, with ammonia, ammonium carbonate or sodium carbonate,

' followed by washing and drying. The proof alcohol or acetaldehyde.

The temperature of reaction must be as low as ssible in order to avoid decomposition an the formation of condensation products, which would take place at higher temperatures. We have found that if eificient catalysts are used, a temperature between 370 and 420 C. will give the best results.

The mixture of acetone and steam, which escapes from the reaction vessel, is referably cooled down only so far that su stantially only the steam is condensed, while the condensation of acetone shall take place only in a second cooling or condensing device. The water resultmg 1n the condensation, after havln been mixed w1th the corresponding quantlty of alcohol or acetaldehyde is re-' turned into the reaction chamber. liy thus proceeding, all losses of acetone and of such quantities of the starting materials or intermediate products, which should'not have been converted completely, are avoided.

Example 1 160 grams ceri-ammonium nitrate and 160 ams stannic chloride hydrate are dissolved in water and after the addition of 300 ams pumice stone the solution is precipitate with ammonia. The catalyst is washed and dried and 6 litres of a watery solution of acetaldehyde containing 720 grams acetaldehyde are conducted over it during 60 hours at 420-430 C. On this condensate being subjected to suitable treatment there are obtained 447 grams acetone=94.3 per cent of the calcuated quantity and 6 grams acetic acid=0.6 per cent, no acetaldehyde being present. The

- quantity of gases split off corresponded to the calculated one, the exhaust gases being composed as follows:

Per cent 00: CO 0 2. 3 H 64. 8

Y Ewample 2 A mixture of 125 grams stannic chloride hydrate and grams crystallized calcium mtrate are dissolved in water, mixed with 230 grams pumice stone, recipitated with ammonium carbonate and t e precipitate filtered by suction, washed and dried. The catalyst thus obtained is placed in the contact oven and 1900 ccms. of-a mixture of acetaldehyde and water containing 227 ms acetaldehyde is conducted d 17 fi ure over the catalyst at 440 C. y suitably treating the condensate. one obtains 180 grams pure acetone, correspondin to 87 per cent of the calculated quantity. 0 obtains further 4.5 grams=1.5 per cent aceticacid,

while 9 grams=4 per cent acetaldehyde are recovere The quantity of gases split of! was equal to the calculated quantity. The gas had the following composition:

C0: Per cent 64. 5 OH. 3. 6

Analogous results are obtained if a contact mass is used which is formed from grams sta-nnic chloride hydrate, 80 grams barium nitrate and 230 grams pumice stone.

Ezvample 8 100 grams cerium chloride and grams stannic chloride hydrate are dissolved in water, 225 grams pumice stone are added and the mixture is precipitated with ammonia. The precipitate is washed and dried and 1600 ccms. of dilute alcohol, containing 240 grams alcohol, are conducted over it at 425v C. within 23 hours. There were obtained grams pure acetone=92.6 per cent of the calculated quantity and 2.1 grams=0.6 per cent acetic acid. The quantity of gases split off was almost equal to the calculated one and the gas was composed as follows:

Per cent C0: 19.7 76. 2 CO 0. 4 CH, 3. 7

Similar results, which were not always as equally favourable as those described before, were obtained with the combination stannous oxide-zinc oxide.

B suitably washing the gases the yield can increased materially.

Example 4 115 grams stannic chloride hydrate and 80 grams barium nitrate are dissolved in water, 230 grams pumice stone are added and the mixture is precipitated with ammonium carbonate. Over the catalyst, after it has been washed and dried, are conducted within 16%; hours at 425 C. 1650 ccms. dilute alcohol containing 224.4 grams alcohol. There were obtained 112 grams pure acetone- 80 per cent of the calculated quantity and 3.4 grams acetic acid=1.2 per cent. The gas split off had the following composition:

00, "33 H 77 CH4 i 3 When operating under the same conditions but using a catalyst being a mixture of stannous oxide and calciumcarbonate substantially the same results were obtained.

Ema'mple 5 160 grams ceri-ammonium nitrate and 160 grams stannic chloride hydrate are dissolved in water, 300 grams pumice stone are added and the mixture is precipitated with ammonia. Over the washed and dried catalyst are conducted at about 425 C. within about 3 weeks (504 hours) litres of a dilute alcohol containing 4600 grams alcohol. There were obtained in this manner 2700 grams acetone=93.3 per cent of the calculated quantity and 30 grams=0.5 per cent acetic acid.

By using acetaldehyde as starting material analogous results were obtained.

Ewample 6 125 grams thorium nitrate and 135 grams stannic chloride hydrate are dissolved in wa-. ter, 225 grams pumice stone are added and the mixture is'precipitated with ammonia. Over the catalyst thus obtained were conducted within200 hours at 440450 C. 16.7 litres of a dilute alcohol containing 2500 grams alcohol. There were obtained 1320 grams acetone= 83.8 per cent of the calculated quantity, 89 grams acetic acid-=27 per cent and 68 grams acetaldehyde=2.8 per cent. The quantity of gases split off corresponded to the calculated quantity and the gas had the following composition:

Percent CO 19.4 C0 0.0 CH 3.8 Hg

In the appended claims the term oxygen? wherein X may be hydroxyl and Y hydrogen or X+Y an. oxygen atom) in the vapour phase together with steam over a contact mass containing a mixture of an oxide of tin with a compound of.. the group comprisin the oxides of the rare earth metals or o thorium, zirconium and zinc and the carbonates of alkaline earth metals.

2. The method of producing acetone which comprises conducting a compound of the formula n orb-0 x (wherein X may be hydroxyl and Y hydrogen or X+Y an oxygen atom) in the vapour phase together with steam over a contact mass containing a mixture of oxides of tin and cerium.

3. The method of producing acetone which comprises conducting ethyl alcohol in the vapour phase together with steam over a contact mass containing a mixture of an oxide of tin with a compound of the oup comprising the oxides of the rare eart metals or of thorium, zirconium and zinc and the car bonates of alkaline earth metals.

4. The method of producing acetone which comprises conducting eth 1 alcohol in the, vapour phase together wlth steam over a contact mass containing a mixture of oxides of tin and cerium.

In testimony whereof we afiix our signatures.

HANS MEERWEIN. HEINRICH MORSCHEL. 

